results are consistent with those of recent graphene experiments by other research groups but provide new quantitative data.

Most significantly, the NIST study shows why friction falls with each sheet of graphene added to the stack (fast scanning also has an effect on the friction). With fewer layers, the top layer deflects more, and the friction per unit of AFM contact force rises. The top surface of the stack becomes less yielding and more slippery as graphene layers are added.

12-01 :: January 2012

By contrast, the friction of three-dimensional gra- phite-like material is virtually unaffected by deforma- tion and rolling friction, and is due instead to heat created by the moving tip.

materials called photonic crystals, using metals such as tungsten or tantalum. The new materials can operate at temperatures up to 1200° C (2192° F). NASA has taken an interest in the research because of its potential to provide long-term power for deep- space missions that cannot rely on solar power.